Bridle for power kite launching

ABSTRACT

A flexible, propulsive wing of the 4-line type especially suitable for kiteboarding, has, at the rear portion of the wing tip a first pulley means attached thereto, the rear line being connected to the rear portion of the wing tip through the first pulley means. A pair of auxiliary re-launch lines are provided at each respective side of the wing, each being fixedly connected at one end thereof to the respective rear line, and at the other end to the trailing edge of the wing.

BACKGROUND OF THE INVENTION

The present invention relates to power kites of the type controlled byat least two forward and two rear lines on each side. In particular, thepresent invention relates to an arrangement of the lines in the form ofa bridle, allowing for easy launching of the kite.

Power kites are a new breed of kites which are designed primarily towardthe sport of kiteboarding, in which a person is pulled along, preferablyon the surface of a body of water, by the force of the kite. It isnecessary for such a kite to be simple to use, yet have sufficientstrength and controllability. A preferred kite is taught by theinventors in U.S. Pat. No. 4,708,078, which is incorporated herein byreference, and which relates to a kite in the form of a spherical gore,with a crescent shaped leading edge, and which is characterized by aninflatable armature.

There are also other variations of power kites, which also rely on alight, flexible structure, but which may, for example, have additionalsupport in the center of the wing to provide a flatter profile at thatpoint. Other kites may have retain the shape of a wing, but may notemploy the spherical gore shape. Nevertheless, all of these kites, inorder to be workable for kiteboarding, must have a degree of flexibilityand should have some curvature at least toward the wing tips. Thesekites are generally characterized by an inflatable structure made oflongitudinal and transversal tubes. Some kites have a “ram air” typestructure as in a paraglider, or a combination of the two. As a whole,these propulsive wing kites can be generally classified as ‘curvedkites’. While it is preferred to use the present invention with the kiteshaped as a spherical gore, it should be clear that the bridle of theinvention can be employed with other curved kites.

A 4-line kite generally has two lines arriving at each of its two ends(or wing tips), a front line forward of the optimum center of lift ofthe kite, that can be called the “center point”, and the rear linebehind the center point. The front lines are preferably fixed to thebody of the rider, for example by way of a belt. The rear lines are usedfor controlling the kite, turning and braking, and are preferablyattached to a control bar.

When using a small kite, with a small aspect ration, the rider can rockthe kite to its side by way of the control lines, in order to positionit for relaunch, by directing the leading edge to catch the wind.However, as the aspect ratio of the kite increases with a larger kite,it becomes more difficult to launch the kite when it has fallen on itsleading edge.

In a 4-line “ram air” kites or others kites whose main lines areattached to bridles, a row of bridles is attached over the entire lengthof the trailing edge. Thus, by pulling on the rear lines, it is possibleto launch the kite positioned on its leading edge, as the kite take canthen launch in “reverse gear”.

It is not effective to use this method on curved kites, however, asmerely connecting the rear lines to a row of bridles fixed on thetrailing edge does not give good results. This method allows forre-launching in reverse gear, but the overall flight qualitydeteriorates due to the overall complexity and unwanted effect of thetrailing edge bridles pulling during flight. It is also possible torelaunch a kite by providing direct lines from the trailing edge to therider, but again the complexity of the additional lines provides anegative effect.

The bridle according to the present invention solves this problem. Itmakes it possible to re-launch a kite with only the basic 4 linesreaching the rider, while also allowing continued flight, turning andcontrol of the power of the kite. Indeed, during normal flight, the rearlines of the inventive bridle work as in traditional 4-line mode,exerting tension on the wing tips; while during launching, this tensionis entirely transmitted to the trailing edge to allow for easy lift in“reverse gear”.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top perspective schematic view of a standard 4-line kite ofthe prior art.

FIG. 2 is a front perspective schematic view of a standard 4-line kiteof the prior art.

FIG. 3 is a top perspective schematic view of a first embodiment of theinvention having re-launch lines affixed between the trailing edge ofthe kite and the rear lines.

FIG. 4 is a side schematic view of the first embodiment, in a positionwherein the pilot has pulled strongly down on the rear lines duringflight.

FIG. 5 is a view of FIG. 4, in a position of normal flight, whereinmedium downward pressure is being exerted on the rear lines by thepilot.

FIG. 6 is a view of FIG. 4, in a position of normal flight, wherein onlylight pressure is being applied by the pilot.

FIG. 7 is a side schematic view of the first embodiment of theinvention, with the kite along the water surface prior to re-launch.

FIG. 8 is a view of FIG. 7, wherein the rear lines have been pulledduring the re-launch effort.

FIG. 9 is a view of FIG. 8, wherein full tension is applied to there-launch lines to achieve re-launch.

FIG. 10 is a side schematic view of a second embodiment of the inventionwith bypass device, shown with front line slack in re-launch mode.

FIG. 11 is a view of FIG. 10, shown in flight mode with bypass devicelocked against first pulley means, and re-launch line slack.

FIG. 12A shows a schematic close-up of the bypass device interactingwith a ring as first pulley means, with the bypass device caught againstthe ring.

FIGS. 12B-D show the view of FIG. 12A with the bypass device andaccompanying portion of the rear line being passed through the ring uponslackening of the front line.

FIG. 13 shows a side schematic view of the second embodiment duringre-launch.

DETAILED DESCRIPTION OF THE INVENTION

A prior art kite of the 4-line type is shown in FIGS. 1 and 2. Withreference to FIGS. 3-6, the front line 2 is fixed forward of the centerpoint 4, as in a known 4-lines kite. However, the rear line 6, insteadof being attached to the wingtip 8 rearward of the center, passesthrough a pulley means 10 fixed at this same location, and then is fixedto the front line 2 at a location 32 between the connection point of thefront line to the kite 14 and the free end 15 of the front line 2connected to the rider 16. It is preferable for the wing tip, from frontto back portion, to have a means for rendering the tip relatively rigid.An additional line, which can be referred to as a re-launch line 18, isattached at one end 20 to the rear line 6 at a location between thenormal contact point of the rear line with the pulley means and the freeend 22 of the rear line 6 connected to the control bar 17. The other end24 of the re-launch line 18 is connected to the trailing edge 26,preferably at a location toward the center thereof.

As long as the kite is in normal flight, the re-launch line 18 is slack(FIG. 6). It has no effect on the flight, and does not slow down thekite even when the pilot makes turns the kite. The length and locationof attachment of this re-launch line should be provided so as to achievethis effect. When the kite falls on its leading edge 28 (FIG. 7), thepilot pulls on the two rear lines 6 until the re-launch lines tightenand draw on the trailing edge (FIGS. 8, 9).

This effect is made possible because of the presence of the pulley means10. During flight, the front lines 2 of the kite are kept taught by wayof the force on the leading edge of the kite (FIGS. 4, 5). This keepsthe rear lines 6 taught as force is transferred to the rear line throughthe front connection point 32. In this manner, a pulling of the rearlines applies force on the wing tip at the point of connection to thepulley means. When the kite falls, the front line slackens, and apulling on the rear lines no longer transfers force directly against thewing tip, as the rear line is not held taught by the front line. At thisstage, a pull on the rear lines draws the lines through the pulleymeans, thus transferring the pulling force to the trailing edge by wayof the re-launch lines (FIGS. 8, 9). The kite starts to fly in reversefashion, trailing edge first, then turns to the leading edge for normalflight after the re-launch is effected. At this time, the pilot slackensa back line and the kite starts to fly ahead and turns.

If the wind is strong, a re-launch can also be achieved by drawing on arear line only. The kite turns then on itself, then, by controlling thetension on a back line, the pilot keeps it on his tip then takes it off.Or, the pilot can draw on the two front lines and the kite takes offdirectly once posed on its trailing edge.

The system as described “gears down” or reduces the amount of requiredexertion on the control bar by the pilot, because of the presence of thepulley means. This also means that the control bar should be movedapproximately twice the distance as compared to a standard 4-line kite,in order to obtain the same effect on the kite. If for example the pilotpulls the bar 20 cm down, this will result in an approximate 10 cmlowering of the rear wing tip.

This effect has an advantage in strong wind and a disadvantage in lightwind, as will be explained. In strong wind, a power kite is generallyvery fast, even dangerous. The fact of gearing down the action on thebar makes the kite less sensitive to the pressures exerted intentionallyor accidentally by the pilot. The result is that the kite is slower toreact, but less prone to sudden changes in direction, and thereby safer.In fact, when a kite (such as a small kite) does not suffer frominherent difficult in launching, the rider may not need the re-launchlines at all. In this case, a particular embodiment of the bridleemploys the pulley means, and the rear line attached to the front lineas set forth above, but without the re-launch lines. The bridleaccording to this embodiment is useful in dampening the reactions of thekite, and providing a safer ride.

In light wind, this reduction in control exertion becomes adisadvantage. Particularly for a large size kite, the pilot must doublethe exertion on the control bar in order to turn the kite or regulatethe power of the kite. For this situation, a second embodiment of thebridle was developed, to allow a re-launching by way of re-launch linesas set forth above, while allowing a bypass of the reduction effectduring normal flight. As shown in FIGS. 10, 11, in this embodiment, theportion 34 of the rear line 6 leaving from the connection point 32 tothe front line 2, does not go directly to the pulley means, which willnow be referred to as the first pulley means 10. Instead, a secondpulley means 38 is located towards the front of the wing tip, preferablyadjacent the location where the front line is connected to the kite. Therear line first passes through this second pulley means 38. As with thefirst pulley means 10, the second pulley means 38 can be a pulley, orany low friction device which maintains the position of the line whileallowing the line to move through that position. As with the firstpulley, the second pulley means may be simply an eye hook or ring,attached to the wing tip to maintain a relatively rigid position, withthe ring oriented generally perpendicular to the plane of the wing tipso that the line is maintained generally parallel to the plane of thewing tip, and preferably generally perpendicular to the direction of thelines running toward the pilot. During re-launch, this second pulleymeans merely redirects the path of the rear line, and the effect of theslackening of the front line on the ability of the pilot to re-launch bypulling on the rear lines, is the same as above. However, a furtherstructure is provided to allow the pilot to bypass the gear down effectof the pulley system during flight.

The bypass device 40 is formed as a structure residing on the rear line6. In the embodiment shown, the bypass device is symmetrical about itslongitudinal axis. The leading end 42 of the bypass device ischaracterized by a slightly sloped shoulder portion 44, radiatingoutward from the center axis aligned with the rear line in almostperpendicular fashion. The radius and degree of slope of the leading endshould be sized such that, when the rear line is drawn in the directionof the leading end of the bypass device (that is, when the rear line ispulled downward by the pilot) the shoulder portion catches against thefirst pulley means, preventing the bypass device from being drawnthrough or around the first pulley means, and therefore holds the rearline against further movement relative to the first pulley means (FIGS.11, 12A). Thus, the radius of the bypass device should be preferablyslightly greater than thickness of the rod forming the ring, but thediameter of the bypass device should be less than the inside diameter ofthe ring, for reasons which will be explained below. Therefore, duringnormal flight, when the rear line is taut (FIG. 11), once the bypassmeans catches on the first pulley means, a further controlling action bythe pilot on the rear lines results in a direct (i.e. not geared down)force on the rear portion wing tip, allowing control by the pilot as ina standard 4-line kite.

When it is required to go to re-launch mode, the pilot, drawing aspreviously explained on the back lines, slackens the front lines (FIGS.10, 13). With respect to FIGS. 12B, 12C, 12D, The bypass device is sizedto allow passage through or around the first pulley means with relativeease when the line is slack. With the line slack, the shoulder does notcatch on the ring (first pulley means) when the rear line is pulled. Asthe bypass device is pulled through the ring, this allows the downwardforce exerted on the rear line by the pilot to be transferred to thetrailing edge by way of the re-launch line. It is for this reason thatthe bypass device should have some degree of slope at its shoulder,leading to a rounded shoulder edge, to allow for the bypass device topass through the first pulley means. Once re-launch is achieved, andnormal flight resumes, the front line pulls tight, thus pulling the rearline tight. As the rear line is pulled tight, the bypass device travelswith a portion of the rear line towards the first pulley means, and thebypass device travels back through the first pulley means. Thus, thebypass device can be shaped at its trailing end 48, away from theshoulder, as a relatively long, steep slope narrowing toward thetrailing end. Upon further drawing on the rear lines during flight, thebypass device against catches against the first pulley means by way ofits leading end shoulder, and normal flight is possible. While thisparticular shape of the bypass device is particularly effective, otherbypass means are also envisioned. Such device needs only to be of astructure which will catch when pressure is exerted, but which willrelease the catch when pressure is released. A ratchet, or mechanicallatch therefore may be possible. For example, first pulley means havingan internal ratchet may be employed. Such a ratchet may allow passage ofthe line when slack, but may grasp the line when the line is tight,which may avoid the necessity of the separate bypass means.

As for the second pulley means, it can be seen that its main purpose isto keep the rear line, and hence the longitudinally shaped bypass meansattached thereto, in a position generally parallel to wing tip (to thedirection of flight) to allow for the bypass device to pass through thering when the line is slack. In the embodiment shown, the second pulleymeans acts to lift the rear line slightly higher (FIG. 10) toward thefront portion of the wing tip, so as to allow the bypass means to passthrough the first pulley means upon slackening of the line (FIGS.12A-D). If second pulley means is not present, then the rear line comingup at an angle, directly from the point of attachment to the front line,presents too severe an angle for this particular shape of bypass device.However, it is contemplated that alternative bypass means structures,such as an internal ratchet, which would not be affected by the angle ofapproach to the first pulley means, would not need the second pulleymeans.

With respect to the connection points 32 of the rear line to the frontline, and the rear line to re-launch line 50, these connections may bemade by any means which will result in a strong, fixed connection. Aknot may be sufficient. Or, a ring or Y-shaped connector may beprovided, to which the ends of the lines may travel or be tied. Thus, itcan be seen that while the front ‘line’ is defined as that lineconnecting the front portion of the wing tip to the pilot, it need notbe a single line. The effect will be the same if three separate linesare connected at front Y junction 32, or if a line runs from the frontwing tip to the Y junction, then along the rear ‘line’ towards the firstpulley means, with a separate line running from the Y junction to thepilot, so long as there is no relative movement between the lines at theY junction. The same point should be understood for the rear Y junction50.

The arrangement of bridle lines can be slightly different to reduce theline lengths or to avoid tangles, this not changing the principle of theinvention. The lengths of lines and adjustments can vary greatlydepending on flying and take off characteristics desired by thedesigner.

What is claimed is:
 1. A flexible, propulsive wing having a leading edgeand a trailing edge extending on either side thereof to wing tips onrespective sides of the wing, each wing tip having at least two linesconnected to and extending therefrom, a front line connected fixedly tothe wing tip towards a front portion thereof, and a rear line connectedto the wing tip towards a rear portion thereof, each of the front andrear lines having a fixed end and a free end, the fixed end of each ofthe front lines being connected to the wing tip, characterised in that:the rear portion of the wing tip comprises a first pulley means attachedthereto, the rear line being connected to the rear portion of the wingtip through the first pulley means, the rear line being fixedlyconnected at the fixed end thereof to the respective front line at alocation of the front line between the fixed end and the free endthereof, the rear line contacting the pulley means at a location of therear line between the fixed end and the free end thereof.
 2. The wing ofclaim 1, further characterised in that a third line is provided at eachrespective side of the wing, each third line being fixedly connected atone end thereof to the respective rear line at a location between thefree end thereof and the first pulley means, the other end of the thirdline being fixedly connected to the trailing edge at a location alongthe trailing edge between the wing tip and the center portion of thetrailing edge.
 3. The wing of claim 2, further characterised in that itcomprises a bypass means for retaining the rear line fixed in positionwith respect to the wing tip when the front line is taut, and forallowing the rear line to move relative to the first pulley means whenfront line is slack.
 4. The wing of claim 3, wherein the bypass means isa bypass structure affixed to the rear line, having an increaseddiameter with respect to the rear line.
 5. The wing of claim 4, whereinthe bypass structure has a leading end radiating outwardly to form ashoulder with a radius and degree of slope which is able to be retainedby the first pulley means when the rear line is taut, but which can movethrough the first pulley means when the line is slack.
 6. The wing ofclaim 5, wherein the bypass structure has a trailing end shaped as atapered end narrowing from the shoulder.
 7. The wing of claim 4, furthercharacterised in that it comprises a second pulley means locatedadjacent the front portion of the wing tip, the rear line running fromthe connection point with the front line, through the second pulleymeans, then through the first pulley means.